Modern technologies are developed prosperously. New information products are provided daily for satisfying people's various needs. The majority of early displays are cathode ray tubes (CRTs). Due to their huge size and power consumption as well as harmful radiation for long-term users, they are gradually replaced by liquid crystal displays (LCDs) at present. LCDs own the advantages of lightweight, small size, low radiation, and low power consumption. Thereby, they have become the mainstream in the market.
In addition, thanks to the rapid progress in the manufacturing technologies of panels in recent years, the manufacturing costs of touch panels has reduced significantly, making them widely applied to general consumer electronic products, such as the small-sized electronic appliances including mobile phones, digital cameras, digital music players (MP3), personal digital assistants (PDAs), and global positioning system (GPS). In these electronic commodities, touch panels are equipped and used as the displays and provides interactive input operations for users. Thereby, the friendliness of the human-machine interface is improved greatly and the input efficiency is enhanced.
In order to provide a larger range of power supply, such as 2.3V to 4.6V, for single-power applications as well as shrinking the area of the driving chips used for driving display panels, driving methods that can satisfy both requirements are proposed. The source driver of a general display device adopts operational amplifiers (Op-amps) or resistive voltage dividing for driving the display panel. Moreover, for making the housing smaller and easier to collocate, raising assembly yield, and reducing costs, shrinking external devices has become an important trend for single-chip liquid-crystal driving chip modules.
FIG. 1 shows a driving circuit for a display panel according to prior art. As shown in the figure, the driving circuit 1′ comprises a plurality of digital-to-analog converting circuits 10′ and a plurality of driving units 20′. The plurality of digital-to-analog converting circuits 10′ receive input pixel data, respectively, and convert the input pixel data to a pixel signal. Then they transmit the pixel signal to the driving units 20′ for producing a driving signal. The driving units 20′ transmit the driving signal to the display panel 2′ for displaying. The driving circuit 1′ according to the prior art is connected externally to a voltage booster circuit 30′. For maintaining the level of the output signals of the digital-to-analog converting circuit 10′, the voltage booster circuit 30′ needs to couple to a storage capacitor 40′. Nonetheless, the capacitance of the storage capacitor 40′ needs to be large (about 0.1 uF). Thereby, the storage capacitor 40′ needs to adopt an external capacitor, which increases the manufacturing cost. If the storage capacitor 40′ is disposed in the driving circuit 1′, the area of the driving circuit 1′ is increased.
Accordingly, the present invention provides a novel area-saving driving circuit for a display panel, which can shrink the area of the storage capacitor connected externally to the driving circuit. Alternatively, the external storage capacitor is even not required. Hence, the problems described above can be solved.